Defect Compensation and Imaging Method for Variable-thickness CFRP Plates Using SH-EMAT

This paper investigates the application of the quasiSH0 mode for damage imaging in anisotropic structures with variable thickness. The non-dispersive characteristics of wave speed in the low-fd states are established through dispersion curve and wave structure calculations. Additionally, the utilization of the elastic dynamics reciprocity theorem reveals the non-dispersive directivity of this mode in the low-fd states. Exploiting these inherent characteristics, we propose an integrated imaging method that incorporates direct and reflected wave information, employing a matching pursuit algorithm, cross-correlation analysis, probabilistic reconstruction, and the delay-and-sum method. Experimental validation conducted on flat CFRP plates and variable thickness CFRP plates underscores the quasi-SH0 mode’s insensitivity to structural thickness variation, thereby enabling effective imaging of damage in such anisotropic structures. These findings offer a pragmatic solution to the formidable challenge of guided wave non-destructive testing in variable thickness CFRP structures.